Air pollution levels in Oxford continue to improve in 2024

However, despite improvements, there continues to be no safe level of air pollution. 

Latest data from Oxford City Council has found that during 2024, overall NO2 levels in Oxford decreased by 10% on average compared to 2023 levels – with some areas seeing decreases of up to 24% –  and a 38% decrease overall on pre-pandemic (2019) levels. 

The data follows the publication of Oxford City Council’s latest Air Quality Annual Status Report for 2024 which examines air pollution levels across 118 locations in the city from January 2024 – December 2024. 

According to the latest NO2 data, Oxford met all UK legal limits for NO2 at all sites of relevant public exposure, with one site in breach of the UK’s legal target (Headington Hill). In addition, the city is on track to meet its local NO2 target by the end of 2025, with only four locations exceeding this target, with just one site in a location of public exposure. 

Monitoring air pollution 

Nitrogen dioxide (NO2) is measured in micrograms in each cubic metre of air (μg/m³), with the legal annual mean target set by Government of 40 μg/m³. 

In 2021, the World Health Organization (WHO) published new guidelines which recommended stricter limits on the ‘safe’ level of air pollution, including PM2.5 and NO2, advising that there is no level at which pollutants stop causing damage.   

In Oxford, there are two annual mean targets for Nitrogen dioxide (NO2) air pollution: 

• National legal limit: the annual mean concentration of NO2 which must not exceed 40 μg/m³
• Oxford’s own adopted local annual mean target for NO2 of 30 µg/m3  

Oxford City Council has a statutory duty to report on air quality within the city and gathers data from each monitoring station within the city, following detailed technical guidance from DEFRA. 

Report highlights: 

Some of the highlights of the latest report are: 

• On average, NO₂ levels fell by 10% in 2024 
• In areas of high bus traffic - such as High Street and St Aldates - there were reductions of up to 24%, largely due to the introduction of ZEBRA funded electric buses in January 2024 
• Oxford met all UK legal limits for NO₂ at all sites of relevant public exposure 
• Only one site was found to be in breach of the UK’s legal target. This is in an area with limited public exposure to air pollution (eg busy roads away from residential areas or areas with pedestrians): 
  • Headington Hill measured a concentration of 43 μg/m³. While still 7% (3 μg/m³) over the legal target, this is a 19% reduction compared to in NO₂ levels in 2023 (53 μg/m³). 
• Only four of the 118 sites were found to be in breach of Oxford’s local annual mean target for NO₂: St Clements (34 μg/m³), with the other three located in areas of limited public exposure: Headington Hill (43 μg/m³), and Oxford’s ring road (32 μg/m³ and 31 μg/m³). 
• Over the past decade (2013 - 2023), average NO2 levels in Oxford have decreased by 52% 

The full air pollution report is available to view here 

Impact of electric buses 

While NO₂ levels fell by 10% on average, areas of high bus traffic - such as High Street and St Aldates saw reductions of up to 24%. This is believed to be largely due to the introduction of 159 ZEBRA funded electric buses from January 2024. 

In February, the Council published an updated source apportionment study for Oxford, which found that the transport is the largest contributor to nitrogen oxides (NO + NO₂) emissions, accounting for 44% of the total emissions of these pollutants. 

The Source Apportionment Study modelling suggested that there was a 12% drop in road transport NOX emissions (from 40% to 32%), with buses now contributing only 4% to total NOX emissions. This reflects a significant (28%) reduction since the previous source apportionment study. 

The latest air pollution data supports this modelling, with the 24% reduction on High Street (reduction from 27 to 21 μg/m³) and St Aldates (reduction from 31 to 23 μg/m³)  largely attributed to the introduction of the ZEBRA scheme electric buses, which now covers 69% of Oxford’s total bus mileage. 

ZEZ Pilot 

In February 2022, the Oxfordshire County Council and Oxford City Council launched the UK’s first Zero Emission Zone (ZEZ) pilot in Oxford. 

In 2024, NO₂ levels within the ZEZ Pilot area overall remain well below both the UK’s legal limit of 40 μg/m³ and Oxford’s local target of 30 μg/m³ 

• NO₂ levels have generally remained stable at locations that are largely pedestrianised: Cornmarket (15 μg/m³), New Inn Hall Street (14 μg/m³), and St Michael’s Street (14 μg/m³). 
• Pedestrianised areas that are shared with buses and taxis (Queen Street, Bonn Square, and New Road) saw the largest reductions in NO2: 
• Queen Street: 17 μg/m³ - a reduction of 4 μg/m³ 
• Bonn Square: 18 μg/m³ - a reduction of 2 μg/m³ 
• New Road: 16 μg/m³ - a reduction of 6 μg/m³ 

Low Traffic Neighbourhoods (LTNs) 

All the monitoring locations both inside and on the boundary roads of Oxford’s LTNS showed a decrease in NO₂ levels measured in 2024, compared to 2023.  

• None of the NO2 levels measured both inside and on the boundary roads of Oxford’s LTNS were above the UK legal limit 
• Only one location (St Clements) showed NO2 levels above the city’s local annual mean target for NO2 
• St Clements - historically Oxford’s most polluted street - saw notable NO₂ reductions of 4 μg/m³, 5 μg/m³, and 3 μg/m³ - averaging 34 μg/m³ 
• Between Towns Road also saw a significant reduction of 5 μg/m³ (from 28 to 23 μg/m³) 
• Hollow Way saw a reduction of 2 μg/m³ (from 31 to 29 μg/m³), now meeting Oxford’s local air quality target for the first time 

Particulate pollution (PM2.5 and PM10) 

PM10 and PM2.5 were both monitored by automatic continuous monitors at St Ebbes (urban background) and Oxford High Street in 2024. 

Oxford has consistently met all UK legal limits for PM2.5 in recent years and is now 2 μg/m³ away from achieving the WHO-recommended annual mean of 5 μg/m³ - considered the safest level for human health. 

PM10 annual means for these sites were of 9 and 13 μg/m³. These values are both below the current UK legal annual mean limit of this pollutant (40 μg/m³) and of the WHO recommended annual mean (15 μg/m³). 

Botley road closure 

In April 2023, Botley Road was closed to traffic as part of broader improvement works on the western side of Oxford Railway Station. Since then, NO₂ levels have been monitored at four locations along Botley Road. 

• In 2022, prior to the road closure, the average NO₂ concentration at these sites was 19 μg/m³ 
• In 2023, this dropped to 16 μg/m³ (a 16% decrease) 
• In 2024, the average further declined to 14 μg/m³ - a 2 μg/m³ decrease compared to 2023 levels, and 13% decrease, compared to the 10% city average 

Main arterial routes into Oxford 

On other major arterial roads into Oxford, 2024 monitoring data shows a consistent decline in NO₂ levels: 

• Abingdon Road: saw a 1 μg/m³ reduction (from 24 to 23 μg/m³) 
• Woodstock Road: saw a 1 μg/m³ reduction on average across 3 sites (from 16 to 15 μg/m³) 
• Banbury Road: saw a 2 μg/m³ reduction on average across 3 sites (from 18 to 16 μg/m³) 
• Headington Road/London Road: saw a 2 μg/m³ reduction on average across 3 sites (from 20 to 18 μg/m³) 
• Sunderland Avenue: saw a 2 μg/m³ reduction on average across 5 sites (from 22 to 20 μg/m³) 

Next steps 

The Council’s report will be submitted to the Government to be ratified and approved. 

The Council publishes annual air quality monitoring reports for the city every June, which are all freely available to read on its website. 

The report will also be used to inform the Council's upcoming Air Quality Action Plan, which will be updated in 2026 following public consultation later this year. 

An Air Quality Action Plan (AQAP) outlines the actions that the Council and its partners will take to improve air quality in Oxford within a certain period of time. The Council’s current Air Quality Action Plan can be read here. 

Comment 

“It is great news that air pollution levels are continuing to fall across all areas of the city, that Oxford is are legally compliant in all locations of public exposure, and that we are close to reaching our localised air pollution target. However, it is important to remember that there is ultimately no safe level of air pollution – it always causes us harm. 

“This data provides us with the latest picture on pollution in Oxford and will help inform our upcoming Air Quality Action Plan, which will look at what measures we can take over the next few years to further improve air quality for everyone in our city.” 

Councillor Anna Railton, Deputy Leader, and Cabinet Member for a Zero Carbon Oxford